fix: root → /platform/ redirect via Traefik file config

Docker-compose label escaping mangles regex patterns. Use a separate
Traefik dynamic config file instead — clean regex, proper 302 redirect.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docker-compose.yml

@@ -33,6 +33,7 @@ services:
     volumes:
       - /var/run/docker.sock:/var/run/docker.sock:ro
       - ./traefik.yml:/etc/traefik/traefik.yml:ro
+      - ./docker/traefik-dynamic.yml:/etc/traefik/dynamic.yml:ro
       - acme:/etc/traefik/acme
       - certs:/etc/traefik/certs:ro
     networks: